Polyhydroxyalkanoates (PHAs) are biodegradable plastics which can be used to make, without limitation, films (e.g., packaging films, agricultural films, mulch film), golf tees, caps and closures, agricultural supports and stakes, paper and board coatings (e.g., for cups, plates, boxes, etc), thermoformed products (e.g., trays, containers, yogurt pots, plant pots, noodle bowls, moldings, etc.), housings (e.g., for electronic items) bags (e.g., trash bags, grocery bags, food bags, compost bags, etc.), hygiene articles (e.g., diapers, feminine hygiene products, incontinence products, disposable wipes, etc.) and coatings for pelleted products (e.g., pelleted fertilizer, herbicides, pesticides, seeds, etc.). PHAs have also been used to develop biomedical devices including sutures, repair devices, repair patches, slings, cardiovascular patches, orthopedic pins, adhesion barriers, stents, guided tissue repair/regeneration devices, articular cartilage repair devices, nerve guides, tendon repair devices, bone marrow scaffolds, and wound dressings.
Polyhydroxyalkanoates can be produced by a fermentation process. Existing fermentation methods for producing polyhydroxyalkanoates utilize wild-type or transgenic microorganisms cultured on specific substrates to produce the desired PHA polymer composition. In many cases the polymers of interest are copolymers of the (D)-isomer of 3-hydroxybutyrate copolymerized with one other 3, 4 or 5-hydroxyacids. These copolymers are produced as granular inclusions inside the cells and are random copolymers. The copolymer poly(3-hydroxybutyrate-co-5-hydroxyvalerate) (PHB5HV) and the homopolymer poly(5-hydroxyvalerate) (P5HV) are industrially useful as materials and plastics with the advantage that they are biodegradable and bioresorbable materials. To date these materials have been produced by feeding petroleum derived 5-carbon substrates like 5-hydroxyvaleric acid (5HV) or 1,5-pentanediol to a microorganism which has the capability to metabolize these substrates to the activated monomer 5HV-Coenzyme A and polymerize it by the action of a PHA polymerase to form the PHB5HV or P5HV polymers, PHB5HV and P5HV polymers produced by these methods are only partly made from renewable resources and expensive due to the high cost of the 5-carbon petroleum substrates. It is highly desirable to use non-petroleum renewable carbon substrates as feedstock for the production of PHV5HV and P5HV polymers both to lower cost and to provide materials that are made entirely from renewable resources. It is also desirable to develop processes for the production of these polymers which reduce the production of greenhouse gasses. Suitable renewable resources include carbohydrate feedstocks available from agriculture including one or more feedstocks selected from: starch, sucrose, glucose, lactose, fructose, xylose, maltose, arabinose and amino acid feedstocks including lysine and proline.
Therefore, it is an object of the invention to provide recombinant organisms and processes whereby genes can be introduced in wild-type or genetically engineered polyhydroxyalkanoate producers to create new strains that synthesize monomers, such as 5-hydroxyvalerate, that are produced from substrates that are not derived from petroleum.
A further object of the invention is to provide techniques and procedures to stably engineer recombinant organisms that synthesize PHAs containing 5-hydroxyvalerate either as sole constituent or as a co-monomer.
It is another object of the invention to provide techniques and procedures to stably engineer recombinant organisms that synthesize 5 carbon chemicals such as 5-aminopentanoate (5AP), glutarate, and 1,5 pentanediol (PDO).